1. Field of the Invention
This invention relates to alarm resetting apparatus and more particularly to that class utilizing remotely generated coded tones to selectively re-institute the alarm apparatus into a working condition by shorting a portion of the alarm circuit found to be open circuited.
2. Description of the Prior Art
The prior art abounds with apparatus remotely controlled by utilizing telephone lines. U.S. Pat. No. 3,876,836 issued on Apr. 8, 1975 to M. J. Langan is one such disclosure. Telephone ringing at a remote location is monitored. Counters register one or two rings, as desired. The first ring sets up a gate-inhibiting period and the second ring extends that period. A count of one is applied to means for energizing an outlet or turning on an appliance. The counters are reset at the end of the gate-inhibiting period, as originally established or extended. Supplemental resetting means becomes effective so as to render the system nonresponsive to rings in excess of two. This apparatus utilizes the ringing tones of the telephone to operate the appliance circuit.
U.S. Pat. No. 3,783,193 issued on Jan. 1, 1974 to M. L. Lee discloses an apparatus for the activation of a remotely located device under the control of telephone subscriber lines and stations. The apparatus is located in the vicinity of a called telephone subscriber station and is operated to activate a remotely located device through two series of ringing signals initiated by a calling telephone subscriber station and produced by the called telephone subscriber station. The first series of ringing signals activates a timer which resets a counter that controls the operation of the remotely located device providing the counter is not on a preselected code position. The timer disables the counter from receiving counting pulses during the first series of ringing signals. In addition thereto, the timer enables the counter to receive the counting pulses during a period P.sub.2 and be a preselected number of ringing signals, the counter will then activate the remotely located device. The Lee Patent is similar in overall function to the Langan Patent.
U.S. Pat. No. 3,400,219 issued on Sept. 3, 1968 to K. U. Jahns et al teaches a remote control system responsive to direct current potentials of different amplitudes and polarities on wire line, and including a plurality of control devices responsive to alternating current signals. The potential on the wire line is applied to the gates to overcome the reverse bias thereon so that the alternating current signals actuate the control devices. Here, injected signals, provided by the oscillator, are utilized to control the actuation of the control devices.
All of the aforementioned patents fail to provide a telephone ringing signal responsive device sensitive to a preset electrical circuit status within the "called" equipment, which in turn enables a successfully completed incoming call during which external coded tones are transmitted, to re-alter the electrical circuits status by automatically determining and modifying the internal circuitry of the called apparatus.